Abstract

Background : Impingement ensures a narrow arc of pathologic loading in adolescent hips with sequelae of Perthes Disease. Proper surgical interference when the hip is still in the pre-arthritic stage restores function and protects the young hip from early degenerative changes. Methods : Osteochondroplasty at the femoral headneck junction and relative lengthening of the femoral neck by distal transfer of the greater trochanter was performed for 12 adolescents with combined intra-articular/extra-articular impingement due to sequelae of Perthes disease in terms of coxa magna, coxa plana, coxa brevis, with an overriding greater trochanter. The safe surgical hip dislocation approach was performed in all cases. Patients were followed for an average of 24 months. Results : The Harris hip scores improved from an average of 58 preoperatively (range 50 to 69) to 94 postoperatively (range 91 to 97) at latest follow up. The range of hip flexion improved from a preoperative value of 84.2° (range, 60 to 105°) to value of 120.8° (range, 95 to 130°). Changes in hip flexion averaged 28.6° (range, 15 to 45°). Mean internal rotation increased to 26° ± 12°, and abduction to 38° ± 11°. Alpha angle improved to 40° ± 8°. The mean of center-trochanteric distance improved from an average of -18 mm to -1 mm. No osteonecrosis or chondrolysis was noted up to the time of the latest follow up. Conclusion : Elimination of narrow arc of pathologic loading due to impingement is the main advantage of the proposed surgical technique. Other advantages include increased abductor lever arm and restoration of hip joint range of motion with normalization of the loading conditions, and hence future development of degenerative arthritis and the anticipated need for a future joint replacement surgery could be prevented or delayed. Femoral head vascularity is well maintained with the proven safety of the presented surgical approach.